Machine for slitting tubular fabrics

ABSTRACT

A machine for slitting a tubular knit fabric while traveling in its longitudinal direction along a substantially longitudinal marking line in or on the fabric which may deviate considerably from a straight course. The cutting device is mounted on a carriage which carries an optical tracing device which traces the marking line and causes the carriage together with the cutting devices to be shifted in a direction substantially transverse to the direction of travel of the fabric toward one or another spreading device which hold the tubular fabric distended for being slit. The time required for this transverse movement of the carriage is compensated by automatically reducing the speed of travel of the fabric. If the marking line deviates excessively from a straight course, the carriage will actuate suitable means for twisting the tubular fabric about its axis so as to move the marking line to its proper position.

United States Patent [191 Letsche MACHINE FOR SLI'I'IING TUBULAR FABRICS [75] Inventor: Hermann Letsche, Genkingen,

Germany [73] Assignee: Maschinenfabrik Arbach, G.

Grozinger, Reutlingen, Germany [22] Filed: June 20, 1972 [21] Appl. No.: 264,471

[30] Foreign Application Priority Data [111* 3,776,077 [451 Dec. 4, 1973 Primary Examiner-J. M. Meister Attorney-Paul M. Craig, Jr. et al.

[ ABSTRACT A machine for slitting a tubular knit fabric while traveling in its longitudinal direction along a substantially longitudinal marking line in or on the fabric which may deviate considerably from a straight course. The cutting device is mounted on a carriage which carries an optical tracing device which traces the marking line and causes the carriage together with the cutting dcvices to be shifted in a direction substantially trans verse to the direction of travel of the fabric toward one or another spreading device which hold the tubular fabric distended for being'slit. The time required for this transverse movement of the carriage is compensated by automatically reducing the speed of travel of the fabric. If the marking line deviates excessively from a straight course, the carriage will actuate suitable means for twisting the tubular fabric about its axis so as to move the marking line to its proper position.

14 Claims, 6 Drawing Figures MACHINE FOR SLITTING TUBULAR FABRICS The present invention relates to a machine for slitting tubular fabrics in which the tubular fabric while distended by means of spreaders is drawn past a cutting device which follows a marking in the fabric.

The slitting machines as are presently known are only suitable for slitting dry tubular fabric which must be fed to the slitting machine in a very proper condition. The spreaders usually consist of a pair of rods which are adjustable to different distances from each other, and the cutting device is mounted in a fixed position adjacent to one of the Spreaders; If the line along which the tubular fabric is to be slit is marked at all on the fabric, it is only possible to twist the tubular fabric by hand in front of the cutting device so that the cutting blade will slit the fabric as accurately as possible in accordance with the marking. These slitting machines do not permit tubular fabrics to be accurately slit along a longitudinal marking if the fabric is fed to the machine in an irregular condition, for example, in a wet or moist condition after a previous treatment, in which the marking cannot be traced or deviates too much from a straight line. Before such a tubular fabric can be slit, it is therefore always necessary first to dry it and in this drying operation also to straighten it so that it will be slit in the proper position.

For slitting flat fabrics into individual widths in the direction of their direction of travel, a slitting machine is already known in which the cutting device is mounted on a carriage which is movable in a direction transverse to the direction of travel of the fabric. This transverse movement of the carriage is controlled automatically by a photoelectric tracing or scanning device which actuates a servo-motor. The scanning device is responsive to a marking line on the fabric which might be either lighteror-darker than the body of the fabric and thus contrasts with the latter. Ifthe scanning device loses the marking line, the entire machine will be immediately stopped. Although this machine has been used extensively for slitting flat fabrics into uniform widths, its proper operation requires the marking which causes the contrast in brightness to be in relatively accurate alignment with the cutting device and the direc tion of travel of the fabric since the carriage on which the cutting device is mounted is movable only for a limited distance and also only with a limited speed. If the marking is too irregular and not sufficiently straight, the scanning device would lose the marking too often and stop the entire machine whenever this occurs. If this happens too frequently, the operation of the machine may become uneconomical.

It is an object of the present invention to provide a machine for slitting tubular fabrics which is especially adapted to slit such a fabric very accurately along a longitudinal marking line which is provided on or in the fabric, even though the tubular fabric is fed to this slitting machine in a very irregular condition and may consist, for example, of a moist or wet fabric which is knit of synthetic fibers, for example, a tubular fabric which is considerably twisted by a preceding centrifugal treatment.

For attaining this object, the invention provides the cutting device to be monuted on a carriage which is adjustable in a direction transverse to the direction in which the tubular fabric and the marking thereon is drawn, and which when moving transversely from its central position in accordance with a deviation of the marking from its straight direction causes the drawing speed of the machine to be reduced accordingly. The tubular fabric may thus be slit in accordance with its marking even if the latter deviates considerably from a straight line and from the direction in which the fabric is drawn since by reducing the speed at which the fabric is drawn, the speed at which the carriage is shifted transversely will be sufficient to permit the cutting device to follow even a very considerable deviation of the marking without losing the latter which, if it did occur, would cause the entire machine to be stopped. Consequently, the speed of travel of the fabric i.e. the speed at which it is drawn through the machine will be adapted to the particular condition of the tubular fabric and if the fabric is, for example, considerably twisted, the machine will run at a lower speed than if the fabric is only slightly twisted or if its marking even runs in a straight direction.

According to one preferred embodiment of the invention, the carriage on which the cutting device is mounted is provided with an optical or photoelectric scanning or tracing device which may, for example, be similar to the scanning device as previously described and is responsive to a contrast in brightness of the tubular fabric which forms the marking line along which the tubular fabric is to be slit and which may be formed, for example, by a run in the fabric. This scanning device controls the operation of a servomotor which, in turn, automatically moves the carriage. In order to permit the slitting machine to be easily adjusted in accordance with marking lines or marking stripes of different width in different tubular knit fabrics, the cutting device itself may be adjustable on its carriage. The cutting device may therefore be properly adjusted to its normal cutting position before the machine is started.

Another feature of the invention consists in connecting the carriage by a rack or the like to a rotary potentiometer with a central tap which is connected in series with the variable drive means for drawing the fabric through themachine. If the tubular fabric does not have to be slit very accurately along the marking line, the rotary potentiometer may be designed so that as long as the marking line deviates only slightly from a straight direction, the fabric will be drawn at the full speed through the machine.

Another object of the invention is to provide suitable means for adjusting the tubular fabric in the event that the marking line of the fabric deviates to such an extend from a straight direction that the optical or photoelectric scanning device can no longer follow this line and loses the same because it passes'beyond the distance within which the carriage is movable on which this scanning device as well as the cutting device are mounted or because, even if a very large carriage is provided, the length of time required by the carriage to follow such an excessive deviation of the marking line would require the speed of travel of the fabric to be excessively reduced. For attaining this object, the invention further provides that the Spreaders which distend the tubular fabric to permit it to be slit consist of basket-like elements which may be turned back and forth about their axes in a direction transverse to the direction of travel of the fabric through the machine. The common drive means for turning these baskets are controlled by switches which are actuated by the mentioned carriage. Therefore, in the event that the marking line is about to deviate beyond the range of the adjustability of the carriage and to be lost by the scanning device or if the adjustment of the carriage requires too much time, it is no longer necessary to stop the entiremachine, but the carriage will then cause the tubular fabric to be shifted transversely to its normal direction of travel until the marking line is again substantially within its normal position and within the range of the adjustability of the carriage According to another embodiment of the invention, the last-mentioned object may also be attained by depositing the tubular fabric which is to be slit within a container which is mounted on a turntable. In the event that the marking line is about to be lost by the scanning device, this turntable is turned in one or the other direction by the actuation of switches which is controlled by the carriage so that the marking line will again be moved back automatically to its normal course and into the area of the adjustability of the carriage.

According to a structurally very advantageous embodiment of the invention, the carriage is provided with cam projections which are preferably adjustable and are adapted to actuate the switches for the means for driving the mentioned spreading baskets and/or the turntable.

For insuring that the tubular fabric itself will be turned immediately if the marking line deviates excessively from a straight direction, it is another feature of the invention to operate the drive means of the baskets and/or the turntable continuously and to provide between these drive means and the baskets and/or the turntable a reversing clutch or reversing gear which may be very quickly controlled by the carriage and when actuated immediately turns the baskets or the turntable at their full speed.

Another feature of the invention consists in providing the spreaders in the form of three baskets which are located within the corners of a triangle, and in mounting the carriage so as to be movable along one side of this triangle. This triangle arrangement of the baskets permits the tubular fabric to be properly distended and it also permits a light source for an optical or photoelectric scanning or tracing device to be mounted at the inside of the triangle and thus at the inside of the tubular fabric. In order to permit tubular fabrics of different diameters to be slit by the machine, the two baskets at both lateral sides of the carriage as well as the carriage itself are adjustable relative to the third basket which is mounted in a fixed position. A structurally very advantageous feature of the invention consists in securing the means for supporting and guiding the carriage and those of the two adjustable baskets on a common support which is adjustable by means of a spindle and on guide rods in a direction transverse to the direction of travel of the fabric. This spindle may be driven either by hand or by means of a servomotor so as to adjust the machine to the particular diameter of the tubular fabric to be slit.

For driving the baskets independently of their positions relative to each other, the invention further provides these baskets with sprocket wheels around which a common chain extends which also runs over a sprocket wheel of a gearing and is guided at both sides of the sprocket wheels of the adjustable baskets by guide wheels at least one of which preferably also serves as a chain tightener.

The features and advantages of the present invention will become further apparent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which FIG. 1 is a diagrammatic side view of a slitting machine according to the invention;

FIG. 2 is a top view of the machine according to FIG.

FIG. 3 is a perspective view of a part of the machine as seen in the direction of the arrow III in FIG. 2;

FIG. 4 is a diagrammatic illustration of a detail of the same machine;

FIG. 5 is a diagrammatic illustration of another detail of the same machine; while FIG. 6 is a view as seen in the direction of the arrow VI in FIG. 5. I

The slitting machine according to the invention as illustrated in the drawings is designed for slitting tubular knit fabrics, especially of synthetic fibers, and preferably while still in a moist condition, after a preceding centrifugal treatment. This reduces the danger of the formation of folds when the material is being dyed and it also improves the quality of the material by avoiding the distortion of stitches.

The tubular fabric 1 as indicated in the drawings in dot-and-dash lines is fed to the slitting machines within a container 2 in a disorderly condition, for example, while still in a moist or even wet condition. The container 2 which is provided with rollers is moved upon and then locked to a turntable 3 which in the particular embodiment of the invention as illustrated is disposed within a recess in the floor so that its upper surface is level therewith.

The tubular fabric 1 which is withdrawn from the container 2 is stretched by three baskets 4, 5 and 6 which serve as spreaders and are mounted so as to be disposed within the comers of a triangle. Between the two baskets 5 and 6 which limit one side of the triangle a cutting device 7 is provided which slits the tubular fabric longitudinally. After being slit, the fabric 1 is further passed between two obliquely extending guide rods 8 to a triangular unfolding frame 9, the substantially rectangular corner of which is located vertically above the basket 4. From this frame 9 which is preferably adjustable to different inclinations the slit and un folded fabric 1 is drawn off by a driven pair of rollers 10 which is followed by two spreading rollers 11 which are individually driven and around which bands of plastic are helically wound and which are followed by a feed roller 12. This roller 12 is followed by a reciprocating take-ofl' device 13 which deposits the fabric in folded layers flat above each other. The rollers 10, 11 and 12 and parts of the take-0H device 13 are mounted within the walls of a boxlike frame 14 which also contains the transmission elements leading to a motor, not shown, which is mounted on or near the floor.

The cutting device 7 comprises a rotary blade 15 and is mounted on a slide carriage 16 which is movable along a supporting tube 17 which extends transverse to the general direction in which the fabric 1 is drawn and thus also transverse to the axes of the baskets 4, 5 and 6. Carriage 16 is provided with an optical tracing or scanning device which comprises a photoelectric cell 19 which is mounted eccentrically within a rotating disk 18. For slitting the tubular fabric 1, it is moved vertically past the rotating blade 15 and the rotating disk 18, as indicated particularly in FIG. 5. At the opposite side of the tubular fabric to be slit and at the inside of the triangle which is defined by the baskets 4, 5 and 6 a light source 20 is mounted which is directed toward the rotating disk 18. The tubular fabric 1 is provided with a longitudinal marking line, for example, a run, which contrasts from the adjacent parts of the fabric. At each revolution of the disk 18, the beam of light from the lamp 20 will twice intersect this marking line in the tubular fabric 1. If this marking line deviates from its vertical direction, the two moments when the light of the source 20 striking the photoelectric cell 19 intersects the marking line will be unequally spaced from each other. This variation from the normal times of intersection will be employed for producing a control .impulse for shifting the slide carriage 16 along the supporting tube 17. Slide carriage 16 is provided with a motor, not shown, which is adapted to move the slide carriage along the supporting tube 17 which is provided with teeth 21. Slide carriage 16 together with the rotating blade will therefore follow the marking line along which the tubular fabric 1 is to be slit. 7

The cutting device 7 is adjustably screwed uponthe slide carriage 16 so as to permit the blade 15 to be adjusted relative to the marking line.

In a slitting machine which is especially intended for slitting moist or even wet tubular fabrics it may often occur that the tubular fabric will be so highly twisted, for example, due to a preceding centrifugal treatment, that, if the speed of operation of the machine is sufficiently high so as to be economical, the optical tracing device may not be able to follow the marking in the tubular fabric. For automatically attaining the highest possible adjustment of the speed of operation of the slitting machine and thus of the speed of travel of the tubular fabric 1 to be slit relative to the extent to which this fabric is twisted, it is an object and feature of the invention to provide suitable means for reducing the speed of travel or withdrawal of the fabric so as to be dependent upon the distance of travel of the carriage 16 from its central position. For this purpose, the withdrawing mechanism consisting of the drawing rollers 10, the feed roller 12 and the take-off or folding device 13 is driven by a drive mechanism which may comprise, for example, a thyristor-controlled geared motor which is preceded by a rotary potentiometer 24 with a central tap which may be turned by the carriage 16. Carriage 16 is provided with a rack 25 which meshes with a gear 26 which is connected to the potentiometer 24 for tuming the same. The movement of the carriage 16 will thus be immediately transmitted to the drive means of the withdrawing mechanism. If in slitting the tubular fabric small deviations from the marking line may be admissible, the rotary potentiometer 24 may be connected to the carriage 16 so that the potentiometer will not be turned within the central area which corresponds to these admissible deviations and within which the full working speed of the slitting machine will be maintained.

If the tubular fabricis highly twisted, the danger occurs that the distance within which the carriage 16 is adjustable may not be sufficient to compensate the deviation of the marking line. Furthermore, if such a strong deviation of the marking line occurs, the speed at which the fabric is drawn through the machine may be so highly reduced that the slitting operation may no longer be sufficiently economical. For this reason, the invention provides that not only the cutting device 7 for slitting the fabric 1 along the marking line may be adjusted, but that the tubular fabric itself together with its marking line may be turned relative to the cutting device 7. This may be accomplished in two different manners. The first manner consists in turning the turntable 3 together with the container 2 and the tubular fabric 1 therein whichis to be fed to the machine so that when the fabric slides over the baskets4, 5 and 6, the marking line on the fabric will again be in alignment with the cutting device-7. The second manner of attaining this turning of the tubular fabric consists in rotatably mounting each of the baskets 4, 5 and 6 and in providing them with common drive means for turning them in one direction or the other until the tubular material 1 is so untwisted that its marking line is again in alignment with the cutting device 7. Although it may often suffice to provide the machine with only one or the other of these turning means, it is usually advisable to provide both of these means. Depending upon the particular condition of the tubular fabric, it may then be decided ineach case whether will baskets in 5 and 6 or the turntable 3 should be turned or whether bothof these turning means should be employed more or less simultaneously.

Each of the baskets 4, 5 and 6 consists of individual round rods 27 which are secured to two disks 28 which, in turn, are mounted on a shaft 29. Every second rod 27 is downwardly extended beyond the lower disk 28 and bent toward the center so as to form a conical starting end of each basket. The lower ends of these extended rods 27 are secured to a hemispherical cup 30. Above the rods 27, the shafts:29 are rotatably mounted in housings 31 and 32 which have smooth outer surfaces. Housing 31 has a cylindrical shape and a diameter which is substantially equal to the maximum diameter of basket 4. The upper. part of the housing 32 has a substantially rectangular cross section, as indicated in FIG. 4, and has two cylindrical extensions 33 each of which has a diameter substantially corresponding to the maximum diameter of the basket 5 or 6 thereon. Housing 31 and housing 32 are connected to each other by connecting rods 34, and housing 31 and thus also the basket 4 are mounted in a fixed posidon, while housing 32 and thus the baskets 5 and 6 are adjustable relative to the housing 31 and basket4 so as to permit the size of the triangle which is defined by the three baskets 4, 5 and 6 to be varied in accordance with the diameter of the particular tubular fabric 1 to be slit. The two housings 31 and 32 are adjustable relative to each other by means ofa spindle 35 which maybe turned by hand or, more, preferably, by a servomotor. Housing 32 is screwed upon two lateral brackets36 which carry the cutting device 7 including the carriage l6 and its supporting tube 17 and theassociated control elements. When the baskets 4, 5 and 6 are being adjusted relative to each other in accordance with the diameter of the tubular fabricl to be slit, the cutting device 7 and its associated driving and control elements will therefore also be adjusted accordingly.

At their upper ends, the shafts 29 of baskets 4, .5 and 6 are provided within the housings 31 and 32 with sprocket wheels 37 whichare connected by an endless chain 38. As indicated in FIG. 4, this chain 38 also passes around a sprocket wheel 39 which is mounted on the driven shaft of a worm reduction gear 40. The sprocket wheels 37 of the baskets 5 and 6 are disposed symmetricallyat both sides of a straight line connecting the sprocket wheel 37 of basket 4 with the sprocket wheel 39 of the worm gear 40. Chain 38 passes over two pairs of guide wheels 41 at both sides of the sprocket wheels 37 of baskets and 6, and one guide wheel 41 of each pair preferably forms a chain tightener by being adjustable in suitable guide means. Baskets 5 and 6 may in this manner be adjusted relative to basket 4 without requiring any fundamental change in the geometrical conditions of the structure of the drive mechanism.

Between the worm gear 40 and a motor, preferably an electric motor, not shown, an electrically controlled reversing clutch or reversing gear 42 is provided. After being switched on, this motor will run continuously in one direction. When the movable member of the reversing clutch 42 is shifted to its central neutral position, the rotation of the motor will not be transmitted to the baskets 4, 5 and 6 and if this clutch member is shifted forwardly or toward the rear, clutch 42 will drive the baskets in one or the opposite direction. A similar reversing clutch or reversing gear may also be provided intermediate the turntable 3 and the motor for driving the same.

The reversing clutch or gear 42 and, if provided, a similar reversing clutch or gear for the turntable 3 are controlled by the carriage l6 insofar as the distance of movement of this carriage determines whether the reversing clutch or gear 42 will be in its neutral position in which the baskets 4 to 6 are stopped or whether it will be shifted to one or the other end position in which the baskets will be turned in one or the other direction. As shown in FIGS. 5 and 6, carriage 16 is for this purpose provided on its lower side with a supporting member 43 on which for each reversing clutch or gear 42 three control cams 44, 45 and 46 are provided which are operatively associated with switches 47. These control cams 44, 45 and 46 are preferably secured on the supporting member 43 so as to be adjustable in the direction of the supporting tube 17 of carriage 16. Each of the electromagnetically actuated reversing clutches or gears 42 is associated with circuits each of which contains a switch 47. Switch 47 of one circuit is adapted to be actuated by the control cam 44 and the switch of the other circuit by the control cam 46. A third switch 47 is connected to both circuits and adapted to be actuated by the central control cam 45. The switches 47 are mounted in fixed positions on a crossbar 48 between the two brackets 36.

If carriage 16 leaves its central position as illustrated in FIG. 6, the particular switch 47 will be closed which is actuated by the control cam 45. Both circuits which are adapted to drive the reversing clutch or gear 42 in opposite directions are then ready for being actuated. One of these circuits will be closed when one of the cams 44 or 46 engages upon the associated switch 47 and thereby closes the latter. This circuit will then remain closed by a suitable relay or the like until carriage 16 has again returned to its central position and the control cam 45 opens the associated switch 47.

The position to which the control earns 44 to 46 are adjusted determines the position in the course of travel of carriage 16 in which the drive means of the baskets 4, 5 and 6 or of the turntable 3 are switched on. The position in which each series of cams 44 to 46 is located relative to the other series also determines the order of succession in which the drive means of the baskets and the turntable are switched on.

Although my invention has been illustrated and described with reference to the preferred embodiment thereof, I wish to have it understood that it is in no way limited to the details of such embodiment but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed my invention, what I claim is:

1. A machine for slitting tubular fabrics each having a marking line extending substantially longitudinally thereof, comprising drawing means for drawing said fabric in its substantially longitudinal direction, means for spreading said tubular fabric while being moved by said drawing means, a slide carriage, drive means for moving said carriage transversely to the direction of travel of said fabric, tracing means adapted to trace the course of said marking line on said tubular fabric and to control the movements of said carriage, and control means responsive to the movements of said carriage for reducing the speed of said drawing means if said marking line deviates considerably from a substantially straight course so as to permit said carriage to carry out its transverse movements.

2. A slitting machine as defined in claim 1, in which said tracing means comprise optical means mounted on said carriage and responsive to a contrast in brightness of said tubular fabric formed by said marking line, and further comprising aservomotor adapted to move said carriage and controlled by said tracing means.

3. A slitting machine as defined in claim 2, further comprising means for adjusting the position of said cutting means on said carriage.

4. A slitting machine as defined in claim 2, in which said control means comprise a rotary potentiometer having a central tap connected in series with said drawing means, and transmitting means connecting said carriage to said potentiometer so as to convert the sliding movements of said carriage into rotary movements of said potentiometer.

5. A slitting machine as defined in claim 2, further comprising reversible drive means for turning said tubular fabric about an axis extending substantially transverse to said direction of travel in the event that said marking line excessively deviates from a straight course so as to move said marking line back to said straight course.

6. A slitting machine as defined in claim 5, in which said spreading means comprise three basketlike elements disposed within the corners of a triangle, said carriage being movable back and forth one side of said triangle toward one or the other of two of said basketlike elements.

7. A slitting machine as defined in claim 5, further comprising control means actuated by said carriage for starting said drive means for turning said fabric in one direction or the other when due to excessive deviations of said marking line in one of said directions from said straight course, said marking line moves out of the range of said optical means on said carriage.

8. A slitting machine as defined in claim 7, in which said spreading means comprise basketlike elements laterally spaced from each other and each having a central axis extending substantially in said direction of travel, said reversible drive means connected to said basketlike elements for turning the latter and for thereby turning said fabric in a direction substantially transverse to said direction of travel, said control 9 means comprising electric switch means connected to said drive means and adapted to be actuated by said carriage for starting said drive means.

9. A slitting machine as defined in claim 7, further comprising a container for receiving the tubular fabric to be slit and from which said fabric is passed to said spreading means and then past said tracing means and cutting means, a turntable for supporting said container in a fixed position thereon, said reversible drive means being adapted to turn said turntable about its axis substantially extending in said direction of travel and for thereby turning said tubular fabric in a direction substantially transverse to said direction of travel, said control means comprising electric switch means connected to said drive means and adapted to be actuated by said carriage for starting said drive means.

10. A slitting machine as defined in claim 7, in which said control means comprise control arms on said carriage and electric switch means connected to said fabric-turning drive means and adapted to be actuated by said control cams.

11. A slitting machine as defined in claim 7, in which said reversible drive means comprise a motor adapted to run continuously in one direction, turning means adapted to turn said tubular fabric in a direction substantially transverse to said direction of travel, motion transmitting and reversing means connected to said motor and movable from a neutral position in which said transmitting means run idle to one or the opposite sidethereof in which the rotation of said motor is transmitted to said turning means so as to turn the latter in one direction or the other, said control means comprising switches connected to said motion transmitting and receiving means and adapted to be actuated by said carriage.

12. A slitting machine as defined in claim 8, in which said basketlike elements are disposed within the corners of a triangle, one of said basketlike elements being mounted in a fixed position and rotatable about its axis and the two other basketlike elements being rotatable in the same direction about their axes and being adjustable to different distances from said fixed basketlike element in accordance with tubular fabrics of different diameters.

13. A slitting machine as defined in claim 12, further comprising first supporting means on which said carriage is slidable, and common supporting means on which said first supporting means and said two adjustable basketlike elements are mounted, means for guiding said common supporting means relative to said fixed basketlike element so that the axes of all of said basketlike elements extend substantially parallel to each other, and a spindle for adjusting said common supporting means relative to said fixed basketlike element in a direction transverse to said direction of travel.

14. A slitting machine as defined in claim 13, in which said drive means for said basketlike elements comprise a sprocket wheel mounted on each of said elements, a rotary drive element, a common chain adapted to run around and to engage with said sprocket wheels and said drive element, and guide wheels on both sides of each of said adjustable basketlike elements, at least one of said guide wheels also being adapted to serve as a chain tightener. 

1. A machine for slitting tubular fabrics each having a marking line extending substantially longitudinally thereof, comprising drawing means for drawing said fabric in its substantially longitudinal direction, means for spreading said tubular fabric while being moved by said drawing means, a slide carriage, drive means for moving said carriage transversely to the direction of travel of said fabric, tracing means adapted to trace the course of said marking line on said tubular fabric and to control the movements of said carriage, and control means responsive to the movements of said carriage for reducing the speed of said drawing means if said marking line deviates considerably from a substantially straight course so as to permit said carriage to carry out its transverse movements.
 2. A slitting machine as defined in claim 1, in which said tracing means comprise optical means mounted on said carriage and responsive to a contrast in brightness of said tubular fabric formed by said marking line, and further comprising a servomotor adapted to move said carriage and controlled by said tracing means.
 3. A slitting machine as defined in claim 2, further comprising means for adjusting the position of said cutting means on said carriage.
 4. A slitting machine as defined in claim 2, in which said control means comprise a rotary potentiometer having a central tap connected in series with said drawing means, and transmitting means connecting said carriage to said potentiometer so as to convert the sliding movements of said carriage into rotary movemeNts of said potentiometer.
 5. A slitting machine as defined in claim 2, further comprising reversible drive means for turning said tubular fabric about an axis extending substantially transverse to said direction of travel in the event that said marking line excessively deviates from a straight course so as to move said marking line back to said straight course.
 6. A slitting machine as defined in claim 5, in which said spreading means comprise three basketlike elements disposed within the corners of a triangle, said carriage being movable back and forth one side of said triangle toward one or the other of two of said basketlike elements.
 7. A slitting machine as defined in claim 5, further comprising control means actuated by said carriage for starting said drive means for turning said fabric in one direction or the other when due to excessive deviations of said marking line in one of said directions from said straight course, said marking line moves out of the range of said optical means on said carriage.
 8. A slitting machine as defined in claim 7, in which said spreading means comprise basketlike elements laterally spaced from each other and each having a central axis extending substantially in said direction of travel, said reversible drive means connected to said basketlike elements for turning the latter and for thereby turning said fabric in a direction substantially transverse to said direction of travel, said control means comprising electric switch means connected to said drive means and adapted to be actuated by said carriage for starting said drive means.
 9. A slitting machine as defined in claim 7, further comprising a container for receiving the tubular fabric to be slit and from which said fabric is passed to said spreading means and then past said tracing means and cutting means, a turntable for supporting said container in a fixed position thereon, said reversible drive means being adapted to turn said turntable about its axis substantially extending in said direction of travel and for thereby turning said tubular fabric in a direction substantially transverse to said direction of travel, said control means comprising electric switch means connected to said drive means and adapted to be actuated by said carriage for starting said drive means.
 10. A slitting machine as defined in claim 7, in which said control means comprise control arms on said carriage and electric switch means connected to said fabric-turning drive means and adapted to be actuated by said control cams.
 11. A slitting machine as defined in claim 7, in which said reversible drive means comprise a motor adapted to run continuously in one direction, turning means adapted to turn said tubular fabric in a direction substantially transverse to said direction of travel, motion transmitting and reversing means connected to said motor and movable from a neutral position in which said transmitting means run idle to one or the opposite side thereof in which the rotation of said motor is transmitted to said turning means so as to turn the latter in one direction or the other, said control means comprising switches connected to said motion transmitting and receiving means and adapted to be actuated by said carriage.
 12. A slitting machine as defined in claim 8, in which said basketlike elements are disposed within the corners of a triangle, one of said basketlike elements being mounted in a fixed position and rotatable about its axis and the two other basketlike elements being rotatable in the same direction about their axes and being adjustable to different distances from said fixed basketlike element in accordance with tubular fabrics of different diameters.
 13. A slitting machine as defined in claim 12, further comprising first supporting means on which said carriage is slidable, and common supporting means on which said first supporting means and said two adjustable basketlike elements are mounted, means for guiding said common supporting means relative to said fixed baskEtlike element so that the axes of all of said basketlike elements extend substantially parallel to each other, and a spindle for adjusting said common supporting means relative to said fixed basketlike element in a direction transverse to said direction of travel.
 14. A slitting machine as defined in claim 13, in which said drive means for said basketlike elements comprise a sprocket wheel mounted on each of said elements, a rotary drive element, a common chain adapted to run around and to engage with said sprocket wheels and said drive element, and guide wheels on both sides of each of said adjustable basketlike elements, at least one of said guide wheels also being adapted to serve as a chain tightener. 